Continuous mixing machine for concrete and similar substances



June 20, 1961 J. w. BEDNER 2,989,291

CONTINUOUS MIXING MACHINE FOR CONCRETE AND SIMILAR SUBSTANCES Fileo.July 14, 1958 2 Sheets-Sheet 1 WHIP." -ii I I I I 19 a l8 5 I l5 l2 i3|32l2 40 4142 7 I 38 I I f AU 1 26 I I ,J 3

June 20, 1961 J. w. BEDNER 2,989,291

CONTINUOUS MIXING MACHINE FOR CONCRETE AND SIMILAR SUBSTANCES Filed July14, 1958 2 Sheets-Sheet 2 United States Patent l 2,989,291 CONTINUOUSMIXING MACHINE FOR CON- CRET-E AND SIMILAR SUBSTANCES Julius W. Bedner,287 Marco Polostraat, Amsterdam, Netherlands Filed July 14, 1958, Ser.No. 748,286 4 Claims. (Cl. 259-474) My invention relates to a continuousmixing machine for concrete and similar substances.

Several machines of this kind have been proposed. Such known machineseither do not give a very good mixing and continuity in the mixtureobtained, or they need very much time for the mixing, so that for givendimensions the capacity is quite small.

Thus most mixing-machines for concrete and similar substances operatebatchwise and not continuously. This gives the possibility to mix aslong as necessary, but has the disadvantages of batch discharge, specialmeans for discharging, such as the tilting of the mixing-drum, and asmall capacity by the need to interrupt or decrease the intensity of themixing for discharging the mixture.

My invention aims at removing such disadvantages and giving an improvedcontinuous mixing-machine for concrete and similar substances whichgives, with a high capacity for a given size, an intimate and continuousmixture.

My invention will now be described with reference to the annexeddrawings, from which the several features of a machine according to myinvention will become clear.

In said drawings: I

FIGURE 1 represents a vertical longitudinal section, in part elevationalview, of a mixing-machine according to the invention in a preferredembodiment.

FIGURE 2 represents a vertical end view of the masiderably greaterradial dimension than that of the stationary drum 6. The drum 12 issubstantially cylindrical and has two rims 13 welded thereto forsupporting the. drum and an outer toothing 14 for driving the drum. Thisdrum has a conical part 15 at the left end, engaging from the outside onthe space 10 at the drum 6 and there. is a conical part 16 on this drum12 at the right end, serving as a flaring discharge end for the drum 12.At the left end of the cylindrical part of the drum 12 there is a: rim17 with a corrugated outer shape as given only for part of the peripheryin a dotted line in the upper part of FIGURE 2. This rim 17 engages aroller 18 and thus through a linkage 19 entrains during rotation of thedrum a vibration or shaking of the grid, not shown, arranged between thehopper 3 and the fall pipe 7.

On the frame 1 there is an electric motor 20 driving a? V-belt pulley21, said pulley driving through V-belts a pulley 22 of greater diameter.'The pulley 22 is arranged on a shaft 23, supported in suitable bracketsupon the frame and which, at about the middle of the length of the drum12, is provided with a cog wheel or pinion 24 engaging the toothing 14of the drum 12 for rotating this drum. The shaft 23 is arranged to theright of the verti-. cal center plane of the drum as seen in FIGURE 2.Both to the right and to the left of this vertical center plane a numberof supporting brackets 25 are arranged with supporting rollers on axlessupported for rotation in said brackets, as appears from the drawingsandas. is quite obvious as such. The left bracket 25 as seen in FIGURE 1to the side where the shaft 23 is arranged supports this shaft and thecorresponding supporting roller is arranged chine according to FIGURE 1,as seen from the right in FIGURE 1.

Referring to the drawings the mixing-machine is arranged upon a frame 1,provided with wheels 2. A hopper 3 serves for supplying the substancesto be mixed.

Around this hopper there is a water trough 4 and this trough is,together with the hopper, supported in a supportingstructure 5, fixed tothe frame 1. Belowthe hopper 3 there is arranged a stationary drum 6with a horizontal axis and the substances to be mixed enter this drumfrom the hopper 3 through a fall-pipe 7, opening at its lower end intothis drum. The stationary drum 6 is closed at the left end as seen inFIGURE 1 and is open at the right end. The fall-pipe 7 opens into thisdrum in the proximity of the left end. In the upper end of the fall-pipe7 a closing flap could be arranged, and above this flap a grid; saidflap and grid may be of usual structure and are not shown in thedrawings. There are provided means for shaking or vibrating the grid inorder to prevent clogging and bridge building of the substances to bemixed. The parts necessary for this purpose will in part be describedbelow. They are not shown entirely in the drawing as they have nothingto do with the invention and could also be omitted.

The upper end of a water-supply-pipe 8 opens into the water trough 4,which upper end is closable by means of a closing member 9. Thewater-pipe 8 at its lower end opens into an annular space 10 around theright end of the drum 6. This space 10 is open at the right end. Theflap (not shown) in the upper end of the fall-pipe 7 could be coupled bymeans of a linkage 11 to the actuating means for the water closingmember 9, so that the supply of substances to be mixed is coupled in adesired manner to the supply of water to supply both water andsubstances at the same time in desired mutual quantities.

The right end of the stationary drum 6 opens into the left end of arotatable drum 12. This drum has a conon said shaft 23.

The shaft 23 has, at the front end of the frame, a; sprocket wheel 24,driving a sprocket wheel 25 through a chain, arranged upon a shaft 26,supported in a bearing: 27, arranged on a supporting structure 28. Theshaft 26 extends into the stationary drum 6 and is there providedwith atraverse 29, on which parallel shafts 30 are se cured in equal distancesfrom the center-line of this drum to both sides of the shaft 26. Theseshafts 30 extend in parallel tothe centerline of the drum 6 towards andinto i the left part of the rotating drum 12 as seen in FIGURE 1 andare, at this end, secured to a traverse 31. To this traverse 31 twoparallel shafts 32 are secured, situated in the same plane as the shafts30, but at a greater dis-: tance from the center-line of the drums band12. These shafts 32 extend to the discharge end of the drum 12 and: are,at this end, secured to a traverse 33. The traverses 29 and 31 have theshape of a double crank web. The traverse 31 is shown in FIGURE 2 bymeans of a dotted; line. The traverse 33 has a circular shape as appearsfrom FIGURE 2 and is provided with a conical flaring part 34. An axle35, supported rotatably in a bearing 36 of a supporting structure 37 onthe frame, is secured to the traverse 33. The entire mixing means,formed by the parts 25, 26 and 29-34, is thus supported at both ends inthe bearings 27 and 36 upon the frame independently of the drums 6 and12.

These mixing means are provided on the shafts 30 with flat stirring arms38, secured to these, shafts with their transverse direction inclined sothat they tend to move the substances to be mixed towards the dischargeend of the drum 12. Moreover these stirring arms 38 are, as appears fromFIGURE 2, inclined with respect to a plane A through the two shafts 30in their longitudinal direction. This inclination is preferably such, asis shown in FIGURE 2, that the angle between the longi: tudinal axis Bof each of said. arms and said plane through the shafts 30 differs from9t)? in such a manner that the stirring arms move from the horizontalposition of said plane through the shafts first to a more fiat orhorizontal position, which will be clear from the direction of rotationof these parts as given by an arrow in FIGURE 2. In other words, each ofsaid stirring arms is disposed on its respective shaft with itslongitudinal axis arranged at an acute angle to said plane, the forwardedge of said stirring arm relative to the direction of ro-' tation ofsaid mixing means leading said plane by an acute angle 0.

The stirring arms 38 are displaced with respect to one another on theshafts 30, so that said arms on one shaft 30 are provided between thearms on the other shaft 30, as seen in FIGURE 1 and as measured in thedirection of the center line of the drum 6. These arms 38 areasymmetrically disposed on shafts 30 in such manner that the portionsthereof which extend toward the center are longer than are thoseportions which extend radially outwardly. Moreover a helical blade 39 isfixed to the shafts 30 and leaves an axially central cylindrical spacebetween the shafts 30 entirely free, said blade having only a smallradial dimension. This blade is so inclined that it is adapted to movethe substances to be mixed towards the discharge end.

Stirring arms 40 are provided on the shafts 32, inclined in the samedirections as the stirring arms 38, but having about the same length inboth directions from the shafts 32, said arms 40 leaving a greaterdistance between them and the inner wall of the drum 12 than is thespace left between the arms 38 and the inner wall of the stationary drum6. A helical blade 41 of about the same shape and inclination as theblade 39 in the drum 6 is provided in this part and this bladeconstitutes the elongation of the blade 39. As shown, the helical blade41 and stirring arms 40, secured to shafts 32, are arranged intermediatethe center line of the drum 12 and the periphery of the latter.

Thin metal strips 42 are provided in the drum 12 and fixed thereto, saidstrips making a small angle to the longitudinal direction of the drum sothat they tend to move the substances to be mixed towards the dischargeend of said drum. Moreover these strips are inclined with respect to theradial direction as seen in FIGURE 2, so that in the part of the drum 12which at a given moment moves upwardly, they constitute with the innerwall of the drum a kind of trough for adequately lifting the substancesto be mixed.

In the operation of the plant the substances to be mixed are deliveredto the hopper 3 by metering devices not shown, which could be of knownand usual construction. They deliver the substances to be mixed to thehopper 3 in the correct mutual quantities. For concrete there will bethree metering devices, for sand, gravel and cement respectively. Thesedevices could operate batchwise although the mixing takes placecontinuously. Said substances fall from the hopper 3 into the stationarydrum 6, a possible flap (not shown) in the upper part of fall-pipe 7being opened, so that said substances somewhat uniformly pass this flapunder the influence of the grid and of the fact that the fiap could onlybe opened partially, thus giving a restricted opening. The easiest wayto attain this is to have the flap urged towards the closed position bya counterweight or spring structure and to have it open under theweight, upon it, of the substances to be mixed, thus also opening thewater-flap 9 by said weight through the linkage 11. Thus water from thetrough 4 flows through the pipe 8 to the space 10 and from there entersthe drum 12. The substances to be mixed are already partially mixed inthe drum 6 by the stirring means moving therein and they are moved tothe right as seen in FIGURE 1 by the co-operation of the stirring arms38 and of the helical blade 39. Thereafter the partially mixedsubstances pass into drum 12 and are lifted therein by the metal strips42, fall from these strips after they have reached a certain elevationand so fall into the center of the space in the drum 12, the mixingmeans engaging these falling substances by the stirring arms 40 and thehelical blade 41. The mixture therewith falls substantially through thefree central space between the shafts 32, but is influenced during thisfall by these parts. It will be clear from FIGURE 2 that the fallingmixture is, in the upper part of its falling path, beaten and thrown tothe left as seen in FIGURE 2 by the stirring arms 40 and, in the lowerpart of this falling path, the falling material is thrown to the rightby said arms. Thus the mixture is mixed by alternatively moving it tothe left and to the right and at any time a quantity of the mixture islifted by the strips 42 again and again and dropped thereby allowing itto be acted upon by the mixing means.

It will be clear that it is possible to constitute the stirring arms ina different manner and to combine them with their shafts to corrugatedmembers instead of shafts with flat separate arms welded thereto.

What I claim is:

1. A continuous mixing machine for concrete and similar substances,including in combination a rotatable mixing drum having a substantiallyhorizontal axis, and rotatable mixing means within said drum, the centerof rotation of said mixing means being substantially in the center lineof the drum, said drum being provided with lifting means fixed to itsinner surface, for lifting substances to be mixed, means for rotatingthe drum in one direction and means for rotating the mixing means in theopposite direction, characterized in that the mixing means comprises atleast two spaced substantially parallel stirring mixer members extendingsubstantially parallel to the axis of rotation of the drum and arrangedon different sides of said drum axis the mixing means leaving asubstantial unobstructed free space in the zone of the center line ofthe drum, said stirring mixing members being arranged intermediate thecenter line of saiddrurn and the periphery thereof, each of saidstirring mixing members comprising a shaft extending substantiallyparallel to the axis of rotation of said drum, and a plurality oflongitudinally spaced stirring arms secured to said shaft, each of saidstirring arms being disposed with its longitudinal axis arranged at anacute angle to a plane which passes through said shaft and the centerline of said drum, the forward edge of said stirring arm relative to thedirection of rotation of said mixing means leading said plane by saidacute angle.

2. A continuous mixing machine as defined in claim 1, furthercharacterized in that the stirring arms of one shaft are otfset from thestirring arms of the other shaft.

3. A continuous mixing machine as defined in claim 1, furthercharacterized in that said mixing means includes a helical blade ofsmall radial extension fixed to and surrounding said stirring mixermembers, said blade being so inclined as to provide forward thrust tosubstances undergoing mixing.

4. A continuous mixing machine as defined in claim I, in which saidlifting means comprises a plurality of helically disposed stripssubstantially coextensive in length with the length of the drum andinclined in planes perpendicular to the drum axis, for liftingsubstances to be mixed in the peripheral direction during the rotation.

References Cited in the file of this patent UNITED STATES PATENTS221,364 Ruger et al. Nov. 4, 1879 409,560 Carey et a1. Aug. 20, 1889869,522 Scheifiier Oct. 29, 1907 1,858,796 Wilcoxson May 17, 19321,861,416 Iaeger May 31, 1932 2,080,508 Sackett May 18, 1937 2,700,533Miller Jan. 25, 1955

